Tuesday, January 06, 2004

More on Probability and Design

Joe Carter at The Evangelical Outpost wrote a response a little while back to my post on probability-based arguments for intelligent design. I'm sorry to say that I'm not very familiar with these issues, and that I intend to study them a good deal in the near future. But for now, I have a few things to say in response to Joe's post, and to some of the comments on my post.
To recap: my position was that it is not reasonable to infer a designer of the universe based merely on the fact that there is a low probability of the universe having the properties it would need (and does have) to sustain life. There are two reasons I think that this is the case: first, we can identify actual events that are unlikely to an arbitrarily large degree, without having any reason to infer a designer. Second, we already know that the world exists and has the properties it has, so it is not unlikely to have occurred. Thinking about them now, I believe that these two arguments are more separate than I'd at first recognized.
First Argument: What's so special about unlikely? Here is what I said in my initial post:

Just now, I opened the book to page 61, and discovered the following remarkable thing -- the pattern of the left-most characters in each line on the page, read top to bottom, is "sTvmstvTawcIFseemcuTlormtomibouAanMc'r" ... the probability of that string having occurred on a page by chance is one in (26 * 2 * 2)^38, somewhere on the order of 4.1 * 10^72. But surely that's not remarkable -- it's just what's there. We don't need to posit someone designing the page that way, even though it's fantastically unlikely that it should have turned out just like that. ... Fantastically unlikely things happen every day -- and we can discover true things that are unlikely to an arbitrary degree just by making them conjunctions (for example, even more unlikely than that string's occurrence is that string's occurrence in a paperback book. More unlikely still, that string occurred in a paperback book on a prime-numbered page!

Rusty Lopez and J.P. Carter both took issue with this analogy. In Rusty's words: "The problem with that reasoning is that, even though the even is highly improbable, there is no information being communicated by it. Give me an event with low probability AND high information, and I'll give you an intelligently designed activity." Carter made what is, I think, essentially the same point.
I'm not sure what to make of information being communicated by an event. Maybe they're saying something like this: that's just a random string of letters -- that's not remarkable. You know what would really be impressive, though, is if the left-most characters spelled out a message that we could understand, like "This passage was designed by Joe Designer" (or maybe "B-A-C-H"). I think there are two problems with this kind of reasoning. First, it's not clear that carries information is an intrinsic property of an event (or pattern or whatever) -- rather, it depends on the ability of someone external to the event "reading" it. Put another way, it's very possible to imagine the course of human linguistic history running differently, such that "This passage was designed by Joe Designer" would look like mere gibberish, while "sTvmstvTawcIFseemcuTlormtomibouAanMc'r" would appear to be brilliant poetry.
Second, even if information-bearing were an intrinsic property of an event, what information does the universe convey? More puzzling still, to whom does it convey its information?
Second Argument: We're Obviously Here. I'm running out of time here (the library is about to close) so I won't go into this now in as much detail as I'd like. But think of probability in terms of possible worlds -- a 1% chance of an event's occurrence means that for every world in which it occurs, there are 99 worlds in which it doesn't. Now suppose there is no designer of the universe, and we're here only by random chance. How remarkable would that be? Not very -- the only people in a position to consider the question would be people in universes that were able to support life. It's literally impossible to observe the universe failing to have the necessary properties -- so how could it be reasonable to find it strange to observe them? (A voice in the back of my head tells me that Stephen Hawking has made arguments like this one, but I absolutely am not prepared to declare that as a fact. Anyone know?)